The present invention relates to a novel device for detecting the level of heat generated by a lighting unit.
Recessed lighting fixtures, although aesthetically pleasing, possess a potential for igniting a fire within the structural body supporting the same. Recently, governmental authorities have required that such fixtures be protected by thermostats which interrupt the flow of electricity to the lighting fixture lamp when it is overheated.
U.S. Pat. Nos. 4,131,868 and 4,396,898 disclose the use of thermal protectors in sockets of lamps. U.S. Pat. Nos. 4,216,411 and 4,460,944 disclose thermostats coupled to swimming pool lights.
U.S. Pat. No. 4,388,677 to Druffel represents the use of a thermal protector with a recessed lighting fixture.
U.S. Pat. Nos. 4,420,802 and 4,314,223 show specialized recessed lighting fixture thermal protectors which are adjacent recessed lighting fixtures.
A serious problem arises when insulation is blown into a ceiling or a wall after installation of recessed lighting fixtures. Such insulation surrounding a recessed lighting fixture will prevent the escape of heat from a recessed lighting fixture which may result in a fire.
Unfortunately, conventional thermal protectors for recessed lighting fixtures are not sufficiently sensitive to after-installed insulation. For example, thermal protectors of the type having insulation sensors mount to the junction box of a recessed lighting fixture and operate independently of the heat source, thereof. Such insulation sensors will not be tripped when insulation covers the heat generating portion of the lighting fixture but does not cover the insulation sensor.
Other thermal protectors, such as the one shown in U.S. Pat. Nos. 4,388,677 to Druffel, 4,420,802 and 4,314,223, attach to the housing of a recessed lighting fixture to sense the temperature of the fixture heat conduction. In addition, other potential hazardous conditions are detected by such heat conduction operated thermal protectors, such as mislamping or overlamping, which can result in the generation of excessive lighting fixture temperatures. However, these housing mounted thermal protectors possess a low safety factor (near 2.degree. C.) often resulting in a nuisance tripping characteristic due to multiple demands on this type of thermal protection scheme. That is to say, the normal operating temperature of the lighting fixture raises the temperature of the housing mounted thermal protector to within 2.degree. C. of a temperature which will trip the thermal protector, within tolerances.
A thermal protector that overcomes the shortcomings of the prior art would be a great advance in the lighting field.